Leetcode - 随笔分类(第22页) - neverlandly

Leetcode: Word Search II

摘要：如果跟Word Search做法一样，还按照DFS回溯的方法，逐个检查每个word是否在board里，显然效率是比较低的。我们可以利用Trie数据结构，也就是前缀树。然后dfs时，如果当前形成的单词不在Trie里，就没必要继续dfs下去了。如果当前字符串在trie里，就说明board可以形成这个wo 阅读全文

posted @ 2015-12-18 03:22 neverlandly 阅读(533) 评论(0) 推荐(0)

Leetcode: Rectangle Area

摘要：Find the total area covered by two rectilinear rectangles in a 2D plane.Each rectangle is defined by its bottom left corner and top right corner as sh... 阅读全文

posted @ 2015-12-18 00:48 neverlandly 阅读(324) 评论(0) 推荐(0)

Leetcode: Shortest Palindrome

摘要：本题最简单的思路是从后往前判断子串是否是回文串，然后把后面的弄到前面即可，不过这样仅仅能擦边通过测试 Brute Force: O(N^2), space O(1) DP: O(N^2), space O(N^2) KMP介绍：http://kb.cnblogs.com/page/176818/ 实阅读全文

posted @ 2015-12-17 14:43 neverlandly 阅读(300) 评论(0) 推荐(0)

Leetcode: Combination Sum III

摘要：ind all possible combinations of k numbers that add up to a number n, given that only numbers from 1 to 9 can be used and each combination should be a... 阅读全文

posted @ 2015-12-17 12:56 neverlandly 阅读(262) 评论(0) 推荐(0)

Leetcode: House Robber II

摘要：Analysis: if the last one is not robbed, then you are free to choose whether to rob the first one. you can break the circle by assuming the first hous 阅读全文

posted @ 2015-12-17 12:20 neverlandly 阅读(337) 评论(0) 推荐(0)

Leetcode: Contains Duplicate II

摘要：Given an array of integers and an integer k, find out whether there are two distinct indices i and j in the array such that nums[i] = nums[j] and the ... 阅读全文

posted @ 2015-12-17 07:44 neverlandly 阅读(198) 评论(0) 推荐(0)

Leetcode: Kth Largest Element in an Array

摘要：Find the kth largest element in an unsorted array. Note that it is the kth largest element in the sorted order, not the kth distinct element.For examp... 阅读全文

posted @ 2015-12-17 07:30 neverlandly 阅读(347) 评论(0) 推荐(0)

Leetcode: Contains Duplicate

摘要：Use HashSet: 阅读全文

posted @ 2015-12-17 07:01 neverlandly 阅读(198) 评论(0) 推荐(0)

Leetcode: Minimum Size Subarray Sum

摘要：Haven't think about the O(nlogn) solution. O(n) solution is to maintain a window My solution: shrink as much as possible while maintaining the window 阅读全文

posted @ 2015-12-17 06:52 neverlandly 阅读(289) 评论(0) 推荐(0)

Leetcode: Add and Search Word - Data structure design

摘要：方法1：brute force: search function compares each word with the pattern, time complexity: O(nk), n is number of words in dictionary, k is averge length 方阅读全文

posted @ 2015-12-17 06:46 neverlandly 阅读(619) 评论(0) 推荐(0)

Leetcode: Implement Trie (Prefix Tree) && Summary: Trie

摘要：参考百度百科：Trie树 a trie, also called digital tree and sometimes radix tree or prefix tree (as they can be searched by prefixes) The time complexity to ins 阅读全文

posted @ 2015-12-16 13:45 neverlandly 阅读(529) 评论(0) 推荐(0)

Leetcode: Course Schedule II

摘要：There are a total of n courses you have to take, labeled from 0 to n - 1. Some courses may have prerequisites, for example to take course 0 you have t 阅读全文

posted @ 2015-12-16 12:25 neverlandly 阅读(324) 评论(0) 推荐(0)

Leetcode: Course Schedule

摘要：The hint provided by leetcode is: Hints: BFS: 典型的拓扑排序。原理也很简单，在一个有向图中，每次找到一个没有前驱节点的节点（也就是入度为0的节点），然后把它指向其他节点的边都去掉，重复这个过程（BFS），直到所有节点已被找到，或者没有符合条件的节点（如果阅读全文

posted @ 2015-12-16 11:18 neverlandly 阅读(311) 评论(0) 推荐(0)

Leetcode: Isomorphic Strings

摘要：Best: O(N) time, constant space 复杂度时间 O(N) 空间 O(N) 思路用一个哈希表记录字符串s中字母到字符串t中字母的映射关系，一个集合记录已经映射过的字母。或者用两个哈希表记录双向的映射关系。这里不能只用一个哈希表，因为要排除egg->ddd这种多对一的映射阅读全文

posted @ 2015-12-15 11:46 neverlandly 阅读(333) 评论(0) 推荐(0)

Leetcode: Reverse Linked List

摘要：基本迭代 Time: O(N), Space: O(1) 基本递归 Time: O(N), Space: O(N)递归栈大小阅读全文

posted @ 2015-12-15 11:15 neverlandly 阅读(267) 评论(0) 推荐(0)

Leetcode: Count Primes

摘要：Count the number of prime numbers less than a non-negative number, n.Algorithm: The sieve of Eratosthenes,Referring to Summary: Primes0 and 1 are not ... 阅读全文

posted @ 2015-12-15 03:09 neverlandly 阅读(275) 评论(0) 推荐(0)

Leetcode: Remove Linked List Elements

摘要：set Dummy node 这题有个重要的follow up，就是在一个环里怎么删除节点：参考：http://www.cnblogs.com/EdwardLiu/p/5975748.html 阅读全文

posted @ 2015-12-15 02:24 neverlandly 阅读(268) 评论(0) 推荐(0)

Leetcode: Bitwise AND of Numbers Range

摘要：Given a range [m, n] where 0 maxRange) continue; 9 int mi = (m>>i) & 1;10 int ni = (n>>i) & 1;11 if (mi == 1 && n... 阅读全文

posted @ 2015-12-15 02:14 neverlandly 阅读(217) 评论(0) 推荐(0)

Leetcode: Happy Number

摘要：Write an algorithm to determine if a number is "happy". A happy number is a number defined by the following process: Starting with any positive intege 阅读全文

posted @ 2015-12-15 00:53 neverlandly 阅读(315) 评论(0) 推荐(0)

Leetcode: House Robber

摘要：This particular problem and most of others can be approached using the following sequence: https://leetcode.com/problems/house-robber/discuss/156523/F 阅读全文

posted @ 2015-04-12 03:36 neverlandly 阅读(589) 评论(0) 推荐(0)

随笔分类 - Leetcode